From c70a1ba3df5f8899f24c7a4c7b4fb816080f7037 Mon Sep 17 00:00:00 2001
From: Leo Broukhis <leobru@users.noreply.github.com>
Date: Sat, 7 Jan 2017 17:11:21 -0800
Subject: [PATCH] BESM6: Fixed a bug in multiplication.

Multiplying a negative number by a zero value with a non-zero exponent produced wrong results.
---
 BESM6/besm6_arith.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/BESM6/besm6_arith.c b/BESM6/besm6_arith.c
index 948a6024..175f68da 100644
--- a/BESM6/besm6_arith.c
+++ b/BESM6/besm6_arith.c
@@ -364,7 +364,7 @@ void besm6_multiply (t_value val)
 
     acc.mantissa = l + ahi * bhi;
 
-    if (neg) {
+    if (neg && (acc.mantissa || mr)) {
         mr = (~mr & BITS40) + 1;
         acc.mantissa = ((~acc.mantissa & BITS40) + (mr >> 40))
             | BIT41 | BIT42;